1. Field of the Invention
The present invention is directed to a communications device, such as, for example, a modem, and a method for enabling data communication, and in particular, to an apparatus and method that detects various communication configurations and selects an appropriate communication configuration to establish a communication link.
2. Discussion of Background and Other Information
Traditionally, data communication devices, such as, for example, modems (both analog and digital), have been employed over public switched telephone networks (PSTN) to transmit data between a first location and a second location. Such modems typically operate within a conventional voice band (e.g., approximately 0 through 4 kHz bandwidth) of the PSTN. Early modems transmitted data over the PSTN at a speed of approximately 300 bit/second, or less. Over time, and with the increased popularity of the Internet, faster communication schemes (e.g., modems) were demanded and developed. Currently, the fastest analog modem available (referred to as an ITU-T V.34 modem, as defined by the International Telecommunication Union Telecommunication Standardization Sector (ITU-T)), transmits data at a rate of approximately 33,600 bits/second under ideal conditions. Hybrid digital-analog modems, referred to as ITU-T V.90 modems, can achieve data transmission rates up to 56,000 bits/second under ideal conditions. These modems continue to exchange data within the approximate 4 kHz bandwidth of the PSTN.
It is not uncommon to transfer data files that are several megabytes (MB) in size. A modem that operates utilizing the V.34 modulation requires a long time to transfer such a file. As a result, a need has developed for even faster modems and Internet access methods.
Accordingly, many new communication methods are being proposed and/or developed to transmit high speed or broadband data on the local twisted wire pair that uses the spectrum above the traditional 4 kHz band. For example, various xe2x80x9cflavorsxe2x80x9d (variations) of digital subscriber line (DSL) modems have been/are being developed, such as, but not limited to, for example, DSL, ADSL, VDSL, HDSL, SHDSL and SDSL (the collection of which is generally referred to as xDSL).
Each xDSL variation employs a different communication scheme, resulting in different upstream and/or downstream transfer speeds, and utilizes differing frequency bands of a twisted pair communication channel. A wide range of physical and environmental limitations of the various configurations of the twisted pair wires leads to widely varying expectations of a feasible communication capability bandwidth. Depending on, for example, the quality of the twisted wire pair (e.g., CAT3 wire vs. CAT5 wire), a given xDSL scheme may not be able to transmit data at its maximum advertised data transfer rate.
While xDSL technologies exist and offer the promise of solving the high speed data transfer problem, several obstacles exist to the rapid deployment and activation of xDSL equipment.
Several of the various xDSL schemes permit simultaneous communication on a single twisted pair in the voice band and in a frequency band above the voice band. To achieve a simultaneous voice band and above voice band communication, some xDSL variations require filters, including low pass filters, high pass filters and combinations of filters that are sometimes referred to as xe2x80x9csplittersxe2x80x9d. The filters separate the frequency band that carries voice band communication from the frequency band above the voice band carrying data communication. The use and type of filters may differ between installations.
Recently, there has been technology and market motivation to eliminate or reduce the use of those filters. Thus, for a given communication channel, the presence and/or type of filter is often unknown. There is a need for the communication devices to xe2x80x9cknowxe2x80x9d the existence and configuration of such filters before initiating a communication method, as such filters impacts which communication methods are viable.
Many different xDSL and high speed access technologies solutions have been described in public, proprietary, and/or de facto standards. Equipment at each end of a connection may implement one standard (or several standards) that may (or may not) be mutually compatible. In general, startup and initialization methods of the various standards have been heretofore incompatible.
Line environments surrounding the xDSL data communication schemes, such as, for example, their ability to co-exist with a conventional analog modem that communicates within the conventional voice band (e.g., 0-4 kHz bandwidth), differences in central office equipment, the quality of the line, etc., are numerous, differ significantly, and are complicated. Accordingly, it is essential to be able to determine the capabilities of the communication channel, in addition to being able to determine the capabilities of the communication equipment, in order to establish an optimum and non-interfering communication link.
User applications can have a wide range of data bandwidth requirements. Although a user could always use the highest capacity xDSL standard contained in a multiple xDSL box, in general, that will be the most expensive service, since communication costs are generally related to the available bandwidth. When a low bandwidth application is used, the user may desire the ability to indicate a preference for a low bandwidth xDSL (and hence, a cheaper communication service), as opposed to using a high bandwidth xDSL service. As a result, it is desirable to have a system that automatically indicates user service and application requirements to the other end of the link (e.g., central office).
In addition to the physical composition of the communication equipment and communication channel, high speed data access complexity is also influenced by regulatory issues. The result has been that possible configuration combinations at each end of a communication channel have grown exponentially.
The US Telecommunication Act of 1996 has opened the vast infrastructure of metallic twisted wire pairs to both competitive (CLEC) usage, and the incumbent telephone provider (ILEC) that originally installed the wires. Thus, multiple providers may have differing responsibilities and equipment deployed for a single wire pair.
In a given central office termination, a given communication channel (line) may be solely provisioned for voiceband-only, ISDN, or one of the many new xDSL (ADSL, VDSL, HDSL, SDSL, etc.) services. Since the Carterphone court decision, telephone service users (customers) have a wide range of freedom for placing (i.e., installing and utilizing) communication customer premise equipment (e.g., telephones, answering machines, modems, etc.) on voiceband channels. However, customer premise equipment (CPE) associated with leased data circuits has typically been furnished by the service provider. As the high speed communication market continues to evolve, customers will also expect and demand freedom in selecting and providing their own CPE for high speed circuits using the band above the traditional voice band. This will place increased pressure on the service providers to be prepared for a wide range of equipment to be unexpectedly connected to a given line.
The customer premise wiring condition/configuration inside of the customer premise (e.g. home, office, etc.) and the range of devices already attached to nodes in the wiring are varied and unspecifiable. For a service provider to dispatch a technician and/or craftsman to analyze the premise wiring and/or make an installation represents a large cost. Accordingly, an efficient and inexpensive (i.e., non-human intervention) method is needed to provide for the initialization of circuits in the situation where a plethora of communication methods and configuration methods exist.
Still further, switching equipment may exist between the communication channel termination and the actual communication device. That switching equipment may function to direct a given line to a given type of communication device.
Thus, a high speed data access start-up technique (apparatus and method) that solves the various equipment, communication channel, and regulatory environment problems is urgently needed.
In the past, the ITU-T has published recommended methods for initiating data communication over voice band channels. Specifically, two Recommendations were produced:
1) Recommendation V.8 (09/94)xe2x80x94xe2x80x9cProcedures for Starting Sessions of Data Transmission over the General Switched Telephone Networkxe2x80x9d; and
2) Recommendation V.8bis (08/96)xe2x80x94xe2x80x9cProcedures for the Identification and Selection of Common Modes of Operation Between Data Circuit-terminating Equipments (DCEs) and Between Data Terminal Equipments (DTEs) over the General Switched Telephone Networkxe2x80x9d.
Both Recommendations use a sequence of bits transmitted from each modem to identify and negotiate mutually common (shared) operating modes, such as the modulation scheme employed, protocol, etc. However, both startup sequence Recommendations are applicable only to the conventional voice band communication methods. Further, these conventional startup sequences do not test (and/or indicate) the constitution and/or condition of the communication channel between the modems.
However, line condition information, such as, for example, frequency characteristics, noise characteristics, presence or absence of a splitter, etc., is useful at the time that plural xDSL modems are negotiating a connection, prior to actually connecting to each other, if the communications link is to be successfully established.
Voice band line probing techniques are known in the art and can be used to determine voice band line condition information. Such techniques have been used to optimize a given modulation method, such as, for example, V.34, but have not been used to optimize startup methods and/or communication selection methods. In a set of devices with multiple modulation methods, V.8 or V.8bis has been used to negotiate and then select a particular modulation. After the modulation initiation sequence has started, line probing techniques are used to receive some indication of the condition of the communication channel. If it is determined at that point that a given communication channel can not effectively support a chosen modulation method, time consuming heuristic (i.e., self-learning) fallback techniques are employed by the prior art to try and find a modulation method that works.
In order to establish an improved communication link, a method is required that observes (examines) the line conditions before attempting to select the most appropriate communication method. While techniques have been established to increase the data rate for a given modulation, the prior art does not provide a method for using channel information to aid in the selection of the communication method.
Unfortunately, in the current state of the art, capability negotiations occur without knowledge of the prevailing channel configuration. Explicit knowledge of spectrum, splitting, etc. is vital to the selection of the most appropriate communication mechanism (modulation) decision process.
Definitions
During the following discussion, the following definitions are employed:
activating station (calling station)xe2x80x94the DTE, DCE and other associated terminal equipment which originates an activation of an xDSL service;
answering stationxe2x80x94the DTE, DCE and other associated terminal equipment which answers a call placed on a GSTN;
carrier setxe2x80x94a set of one or more frequencies associated with a PSD mask of a particular xDSL Recommendation;
CAT3xe2x80x94cabling and cabling componenets designed and tested to transmit cleanly to 16 MHZ of communications. Used for voice and data/LAN traffic to 10 megabits per second;
CAT5xe2x80x94cabling and cabling componenets designed and tested to transmit cleanly to 100 MHZ of communications;
communication methodxe2x80x94form of communication sometimes referred to as modems, modulations, line codes, etc.;
downstreamxe2x80x94direction of transmission from the xTU-C to the xTU-R;
errored framexe2x80x94frame that contains a frame check sequence (FCS) error;
Galfxe2x80x94an octet having the value 816; i.e., the ones complement of an HDLC flag;
initiating signalxe2x80x94signal which initiates a startup procedure;
initiating stationxe2x80x94DTE, DCE and other associated terminal equipment which initiates a startup procedure;
invalid framexe2x80x94frame that has fewer than four octets between flags, excluding transparency octets;
messagexe2x80x94framed information conveyed via modulated transmission;
metallic local loopxe2x80x94communication channel 5, the metallic wires that form the local loop to the customer premise;
responding signalxe2x80x94signal sent in response to an initiating signal;
responding stationxe2x80x94station that responds to initiation of a communication transaction from the remote station;
sessionxe2x80x94active communications connection, measured from beginning to end, between computers or applications over a network;
signalxe2x80x94information conveyed via tone based transmission;
signaling familyxe2x80x94group of carrier sets which are integral multiples of a given carrier spacing frequency;
splitterxe2x80x94combination of a high pass filter and a low pass filter designed to split a metallic local loop into two bands of operation;
telephony modexe2x80x94operational mode in which voice or other audio (rather than modulated information-bearing messages) is selected as the method of communication;
transactionxe2x80x94sequence of messages, ending with either a positive acknowledgment [ACK(1)], a negative acknowledgment (NAK), or a time-out;
terminalxe2x80x94station; and
upstream: The direction of transmission from the xTU-R to the xTU-C.
Abbreviations
The following abbreviations are used throughout the detailed discussion:
ACKxe2x80x94Acknowledge Message;
ADSLxe2x80x94Asymmetric Digital Subscriber Line;
ANSxe2x80x94V.25 answer tone;
ANSamxe2x80x94V.8 modulated answer tone;
AOMxe2x80x94Administration, Operations, and Management;
CCITTxe2x80x94International Telegraph and Telephone Consultative Committee;
CDSLxe2x80x94Consumer Digital Subscriber Line;
CRxe2x80x94Capabilities Request;
CLxe2x80x94Capabilities List;
CLRxe2x80x94Capabilities List Request;
DCMExe2x80x94Digital Circuit Multiplexing Equipment;
DPSKxe2x80x94Differential encoded binary Phase Shift Keying;
DISxe2x80x94Digital Identification Signal;
DMTxe2x80x94Discrete Multi-Tone;
DSLxe2x80x94Digital Subscriber Line;
ECxe2x80x94Echo canceling;
EOCxe2x80x94Embedded Operations channel;
ESxe2x80x94Escape Signal;
FCSxe2x80x94Frame Check Sequence;
FDMxe2x80x94Frequency Division Multiplexing;
FSKxe2x80x94Frequency Shift Keying;
GSTNxe2x80x94General Switched Telephone Network (same as PSTN);
HDSLxe2x80x94High level Data Link Control;
HSTUxe2x80x94Handshake Transceiver Unit;
IETFxe2x80x94Internet Engineering Task Force;
ISOxe2x80x94International Organization for Standardization;
ITU-Txe2x80x94International Telecommunication Unionxe2x80x94Telecommunication Standardization Sector;
LSBxe2x80x94Least Significant Bit;
LTUxe2x80x94Line Termination Unit (Central office end);
MRxe2x80x94Mode Request;
MSxe2x80x94Mode Select;
MSBxe2x80x94Most Significant Bit;
NAKxe2x80x94Negative Acknowledge Message;
NTUxe2x80x94Network Termination Unit (Customer premise end);
OGMxe2x80x94Outgoing Message (recorded voice or other audio);
ONUxe2x80x94optical network Unit;
POTSxe2x80x94Plain Old Telephone Service
PSDxe2x80x94Power Spectral Density;
PSTNxe2x80x94Public Switched Telephone Network;
RADSLxe2x80x94Rate Adaptive DSL;
REQxe2x80x94Request Message Type Message;
RFCxe2x80x94Request For Comment;
RTUxe2x80x94RADSL Terminal Unit;
SAVDxe2x80x94Simultaneous or Alternating Voice and Data;
SNRxe2x80x94Signal to Noise Ratio;
VDSLxe2x80x94very high speed Digital Subscriber Line;
xDSLxe2x80x94any of the various types of Digital Subscriber Lines (DSL);
xTU-Cxe2x80x94central terminal unit of an xDSL; and
xTU-Rxe2x80x94remote terminal unit of an xDSL.
Based on the foregoing, the present invention is directed to a communication method, modem device and data communication system that detects various configurations, capabilities and limitations of a communication channel, associated equipment, and regulatory environment in order to determine a specific (xDSL) communication standard appropriate for the existing line conditions. To accomplish this goal, the invention employs several individual techniques as a system.
According to one aspect of the present invention, a method and apparatus are provided to negotiate between modems that embody multiple (plural) communication methods (e.g., DSL standards), so as to select a single common communication standard to be used for a communication session. A communication control section executes a handshake procedure (protocol) in a negotiation channel to obtain information concerning high speed data communication, including type identification information of the xDSL used in the communication exchange. A communication standard refers to any type of standard, whether defacto, proprietary, or issued by an industry or governmental body.
According to another aspect of the instant invention, characteristics of the communication channel between a central communication system and a remote communication system are determined using an examination signal. The examination signal detects impairments, such as, but not limited to, for example, frequency roll-off and noise, that are identified and detected between the central system and the remote systems. Information pertaining to the quality of the communication channel enables the present invention to make an informed decision concerning the selection of a communication standard. (e.g., whether to use CDSL instead of ADSL, or use CDSL instead of VDSL).
The combination of all of the various aspects of the invention provides a method and apparatus for effectively and efficiently performing an audit of the communication channel and installed equipment to select the most appropriate communication method. System designers, installers, and providers are able to predetermine and set various parameters that are considered by the method and apparatus of the present invention during the negotiation process to effectively define the meaning of xe2x80x9cmost appropriate means of communicationxe2x80x9d.
According to the present invention, a procedure to determine a possible high speed communication, and selection of supported capabilities for a high speed data communication, and the examination of the communication line characteristics may be concurrently (simultaneously) executed, thus enabling the immediate shifting to a handshake protocol corresponding to the determined data communication procedure. In this regard, it is understood that the procedure may also be sequentially executed.
The invention may be included in both sides of the communication channel for optimum negotiation. However, according to an advantage of the present invention, the invention can be incorporated into (contained in) just one side of the communication channel. Such configurations will be accurately reported to the communication systems, and, if appropriate, the communication systems can fall back to legacy (e.g., analog) communication methods, if the communication system provides such support.
The instant invention does not need to be embodied in the actual high speed communication devices, but may be implemented in intelligent switches that terminate and/or segment the communication channel. This allows a communication system to use various communication standards implemented in separate devices (or modems) that can be correctly assigned (on a xe2x80x9cas neededxe2x80x9d basis) through explicit negotiation of the capabilities and requirements of the central system and the remote communication system.
According to an advantage of the present invention, an environmentally friendly method for selecting start-up carriers is provided.
According to another feature of the present invention, ITU-T G.997.1 may be used to configure the information field registers.
According to another advantage of the instant invention, a unique data format, coding format and data structures for messages is provided.
According to an object of the instant invention, an apparatus for establishing a communication link, comprises a negotiation data transmitting section, associated with a plurality of initiating communication devices, that transmits carriers to a responding communication device, a negotiation data receiving section, associated with the plurality of initiating communication devices, that receives carriers from the responding communication device, in response to the transmitted carriers, and a selecting device that selects an appropriate communication device from the plurality of communication devices, in accordance with the responding communication device, so as to establish a communication channel.
According to a feature of the invention, the transmitted carriers contain data related to a useable carrier allocation. In addition, the transmitted carriers and the received carriers may be divided into a plurality of bands. A system selects a plurality of bands to minimize interference with a voice band device.
An advantage of the instant invention is that the negotiation data transmitting section transmits the carriers in accordance with neighboring receiving systems. The transmission characteristics of the transmitted carriers are re-configurable during a transmission operation in order to minimize interference with the neighboring receiving stations.
According to an object of the instant invention, a method is disclosed for establishing a communication link. The method transmits predetermined carriers to a responding communication device, receives predetermined carriers from the responding communication device, in response to the predetermined transmitted carriers, and selects an appropriate communication device from a plurality of communication devices, in accordance with the received predetermined carriers, to establish a communication channel.
A feature of this object of the invention includes the dividing of the transmitted carriers and the received carriers into a plurality of bands.
Another feature of this invention is that the transmitting of predetermined carriers comprises transmitting the carriers in accordance with neighboring receiving systems. The transmitting of transmission characteristics of the carriers comprises re-configuring the carriers during a transmission operation in order to minimize interference with the neighboring receiving stations.
Another object of the instant invention is to provide a communication device that at least one of transmits and receives a communication signal, comprising a data exchanging device that exchanges data, between an initiating communicating device and a responding communication device, over a communication channel, and an implicit channel probe device that analyzes the exchanged data to assess characteristics of the communication channel.
The data exchanging device of this invention comprises a transmitter that transmits results of the analyzed exchanged data as part of the exchanged data.
The implicit channel probe device comprises an analyzer that monitors the communication channel by performing a spectral analysis of the exchanged data. The exchange of data and the analysis of exchanged data may occur at substantially the same time, or sequentially in time.
According to a feature of the invention, the exchanged data comprises a plurality of initializing carriers, the plurality of initializing carriers being exchanged between the initiating communicating device and the responding communication device.
According to another object of the instant invention, method for at least one of transmitting and receiving a communication signal is disclosed, comprising the exchange of data between an initiating communicating device and a responding communication device, over a communication channel, and the performing of an implicit channel probe analysis on the exchanged data to assess characteristics of the communication channel.
An advantage of this invention is that the exchange of data comprises transmitting results of the analyzed exchanged data as part of the exchanged data.
Another advantage of the present invention is that the performing of an implicit channel probe analysis comprises performing a spectral analysis of the exchanged data.
According to a feature of the invention, the method further comprises exchanging the data and performing the analysis at substantially the same time, or, alternatively, sequentially in time.
A feature of the current invention resides in the exchanging of a plurality of initializing carriers between the initiating communicating device and the responding communication device.
Another object of the instant invention pertains to a communication device, comprising a communication device that initially transmits data with a multiplicity of carriers, and a carrier determining device that reduces the multiplicity of carriers transmitted by said communication device to a predetermined number of carriers, in accordance with a predetermined carrier reduction system.
According to a feature of the instant invention, the predetermined carrier reduction system comprises a pair phase reversal system, a modulate carrier system, or a carrier use and request transmit system.
According to another feature of the invention, the carrier determining device comprises a reduction device that reduces the multiplicity of carriers to the predetermined number of carriers in order to limit a transmit power during an initialization procedure.
A still further feature of the instant invention pertains to the carrier determining device, which comprises a determining device that determines the most usable communications channels.
According to this invention, the initial transmission of the multiplicity of carriers comprises a system that increases a likelihood of establishing a communication channel. The carrier determining device reduces the multiplicity of carriers to the predetermined number of carriers to reduce a power transmission requirement.
According to another object of the current invention, a method for establishing a communication link is disclosed, comprising the exchange of unmodulated carriers between an initiating communication device and a responding communication device, to negotiate a high speed communication link, and the execution of a fallback procedure to establish a predetermined communication link if one of the initiating communication device and the responding device is unable to process the unmodulated carriers for negotiating the high speed communication link.
The execution of a fallback procedure comprises executing a predetermined escape procedure to establish a communication link with a legacy high speed communication device, or, alternatively, executing a predetermined explicit connection procedure to establish a communication link with the legacy high speed communication device.
According to a feature of the invention, the execution of the fallback procedure comprises executing a voiceband modulation procedure to establish a voiceband communication link.
A still further object of the present invention pertains to a method for establishing a communication link between a first device and a second device, comprising transmitting a first capabilities list to one of the first device and the second device, receiving a second capabilities list transmitted by a remaining one of the first device and the second device, in response to the first capabilities list, selecting an appropriate communication mode from a plurality of communication modes, in accordance with the second capabilities list, to establish the communication channel, and executing a simplified initialization procedure to re-establish the communication link in the event that one of the first device and the second device has entered a non-data exchange state and data is to be exchanged between the first device and second device.
Another object of the instant invention pertains to a method for establishing a communication link between a first device and a second device, comprising establishing common communication capabilities between the first device and the second device, selecting an appropriate communication mode from a plurality of communication modes, in accordance with the established common communication capabilities, and executing a simplified initialization procedure to re-establish the communication link in the event that one of the first device and the second device has entered a non-data exchange state and data is to be exchanged between the first device and second device.
Another object of the invention pertains to a method for establishing a communication link, comprising executing a negotiation protocol in order to establish a communication link between a first communication device and a second communication device, maintaining a carrier of the negotiation protocol upon establishing the communication link, to serve as an embedded operations channel.
According to a feature of the invention, the embedded operations channel transmits managerial data.
In another object of the instant invention, a communication device is disclosed, comprising means for performing a handshake communication procedure, and means for configuring handshake communication parameters from a terminal using a Simple Network Management Protocol. Further, the communication device may also include means for monitoring the handshake communication parameters from the terminal. In addition, the invention may use an Administration, Operations, and Management (AOM) Simple Network Management Protocol (SNMP) to configure and monitor a handshake procedure for establishing a high speed communication link
The present disclosure relates to subject matter contained in U.S. Provisional Application No. 60/080,310 filed on Apr. 11, 1998; No. 60/089,850 filed on Jun. 19, 1998; No. 60/093,669 filed on Jul. 22, 1998; and No. 60/094,479, filed on Jul. 29, 1998, the disclosures of which are expressly incorporated herein by reference in their entirety.
The present disclosure also refers to the following Recommendations, the subject matter of which is expressly incorporated herein by reference in their entirety:
Recommendation V.8bis (09/94)xe2x80x94xe2x80x9cProcedures for Starting Sessions of Data Transmission over the General Switched Telephone Networkxe2x80x9d, published by Telecommunication Standardization Sector of the ITU;
Recommendation V.8 (08/96)xe2x80x94xe2x80x9cProcedures for the Identification and Selection of Common Modes of Operation Between Data Circuit-terminating Equipments (DCEs) and Between Data Terminal Equipments (DTEs) over the General Switched Telephone Networkxe2x80x9d, published by Telecommunication Standardization Sector of the ITU;
Recommendation T.35xe2x80x94xe2x80x9cProcedures for the Allocation of CCITT Defined Codes for Non-standard Facilitiesxe2x80x9d, published by Telecommunication Standardization Sector of the ITU; and
Recommendation V.34 (10/96)xe2x80x94xe2x80x9ca Modem Operating at Data Signaling Rates of up To 33,600 bit/s for Use on the General Switched Telephone Network and on Leased Point-to-point 2-wire Telephone-type Circuitsxe2x80x9d, published by Telecommunication Standardization Sector of the ITU.